1. Field of the Invention
The invention relates to a lithium battery. Particularly, the invention relates to an electrolyte solution of a lithium battery.
2. Description of Related Art
Since a primary cell does not match a requirement of environmental protection, a secondary battery system capable of being recharged gradually draws attention in recent years. Portable electronic products such as digital cameras, mobile phones and notebook computers all require lightweight batteries. As the portable electronic devices are quickly developed and popularized, a lithium battery capable of being repeatedly charged and discharged becomes popular in the market due to its characteristics of lightweight, high voltage value and high energy density, etc. Compared with a conventional lead-acid battery, nickel-metal hydride battery, nickel-zinc battery, and nickel cadmium battery, the lithium battery has advantages of high working voltage, high energy density, lightweight, a long service life and environmental protection, etc., which is also a best choice in flexible battery application in the future. Therefore, performance requirements of the lithium battery in lightweight and durability, high voltage, high energy density and high security are increased, and the lithium battery has a high application and expansion potential in light electric vehicles, electric vehicles and large power storage industry.
However, according to the conventional technique, the lithium battery has to be fabricated in an environment of high dryness and low water content since the water can be electrolyzed into oxygen and hydrogen during electrochemical reaction of the battery, which may cause battery swelling and performance degradation. Moreover, a side reaction also takes place as high water content in the battery react with lithium salt to form hydrofluoric acid, and such outcome may cause releasing of transition metal ions of an electrode material and erosion of a collector layer, which may easily lead to a dangerous situation of the battery. Since the lithium battery has to be fabricated in the environment of high dryness and low moisture content (for example, under relative humidity<5%), most of the manufacturers have to construct drying chamber and drying plant for production and assembly to cope with the requirement of the fabrication process, so that the lithium manufacturers have to pay a high cost for electricity. On the other hand, an air chamber can be used to perform a secondary package processing procedure to ameliorate the problem of high water content in the battery. The secondary package processing procedure refers to that the plenty water contained in the battery is electrolyzed into gas during a first electrochemical reaction, and a space is preserved in the battery to guide the gas flowing into the air chamber, and then the air chamber is removed to perform the secondary package. Therefore, the fabrication steps for secondary package are complex and time-consuming. However, the aforementioned fabrication processes are all inconvenient and may increase additional fabrication cost.